Split VAT into segments based on Country code

What is the best wat to split any VAT number into segments? First part is the country code, is always 2 alphanumeric. Second is the remaining number.

For example: NL820471616B01 should be split to NL and 820471616B01

BE0824148721 should be split to BE and 0824148721

ATU12345678 should be split to AT and U12345678

I have tried this but that will only suit when there are 2 alphanumeric numbers.

$vat_clean = preg_replace('/[^a-zA-Z0-9]/', '', $_GET['vat']);
$vat_country = substr($vat_clean,2,25);
$vat_code = substr($vat_clean,2);

Answer

Since it appeared the any VAT number starts with 2 alphanumeric numbers I could tweak the existing code to get it fully to work.

$vat_clean = preg_replace('/[^a-zA-Z0-9]/', '', $_GET['vat']);
$vat_country = substr($vat_clean,2,15);
$vat_code = substr($vat_clean,0,2);