Of course.
In the existing API, you’d have something like this (XML):
<Invoice_Create xmlns="https://api.quickfile.co.uk" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="https://api.quickfile.co.uk https://api.quickfile.co.uk/schemas/1_2/Invoice_Create.xsd">
<Header>
<MessageType>Request</MessageType>
<SubmissionNumber>00000001</SubmissionNumber>
<Authentication>
<AccNumber>123456</AccNumber>
<MD5Value>7dd259dea3393880406d292e3f6f5830</MD5Value>
<ApplicationID>appID</ApplicationID>
</Authentication>
</Header>
<Body>
<InvoiceData>
<InvoiceType>ESTIMATE</InvoiceType>
<ClientID>1343151</ClientID>
<ClientAddress>
<Address><![CDATA[123 Test Street<br/>Manchester<br/>MA1 5TH]]></Address>
<CountryISO>GB</CountryISO>
</ClientAddress>
<Currency>GBP</Currency>
<TermDays>14</TermDays>
<Language>en</Language>
<InvoiceLines>
<ItemLines>
<ItemLine>
<ItemID>0</ItemID>
<ItemName>BC1</ItemName>
<ItemDescription>300 Business Cards (250gsm)</ItemDescription>
<ItemNominalCode>4000</ItemNominalCode>
<Tax1>
<TaxName>VAT</TaxName>
<TaxPercentage>20.00</TaxPercentage>
<TaxAmount>20</TaxAmount>
</Tax1>
<UnitCost>100</UnitCost>
<Qty>1</Qty>
</ItemLine>
<ItemLine>
<ItemID>0</ItemID>
<ItemName>EMB1</ItemName>
<ItemDescription>Embossing Stamp</ItemDescription>
<ItemNominalCode>4000</ItemNominalCode>
<Tax1>
<TaxName>VAT</TaxName>
<TaxPercentage>20.00</TaxPercentage>
<TaxAmount>10</TaxAmount>
</Tax1>
<UnitCost>50</UnitCost>
<Qty>1</Qty>
</ItemLine>
</ItemLines>
</InvoiceLines>
<Scheduling>
<SingleInvoiceData>
<IssueDate>2026-09-03</IssueDate>
</SingleInvoiceData>
</Scheduling>
</InvoiceData>
</Body>
</Invoice_Create>
In the new API, you’d have this:
Headers
Authorization: Bearer {{Token}}
Content-Type: application/json
Body
{
"type": "estimate",
"client_id": 1343151,
"client_contact_name": "Jim Smith",
"client_address": "123 Test Street<br/>Manchester<br/>MA1 5TH",
"client_country": "GB",
"currency": "GBP",
"term_days": 14,
"language": "en",
"issue_date": "2026-09-03",
"item_lines": [
{
"item_name": "BC1",
"description": "300 Business Cards (250gsm)",
"nominal_code": 4000,
"vat_rate": 20,
"vat_amount": 20,
"unit_cost": 100,
"qty": 1
},
{
"item_name": "EMB1",
"description": "Embossing Stamp",
"nominal_code": 4000,
"vat_rate": 20,
"vat_amount": 10,
"unit_cost": 50,
"qty": 1
}
]
}
I think I’ve covered everything there, but if I’ve missed anything, please let me know.
The guide I linked to above for the new API is your best reference as this shows you every possible field and what value types it supports. It also has examples of both the request and response.